EP 0282236-A1 describes that a dibenzothiazepine derivative of the above-mentioned formula (5) can be processed to give 11-[4-(2-(2-hydroxyethoxy) ethyl]-1-piperadinyldibenzothiazepine derivative which is of value as an antipsychotic pharmaceutical. In more detail, dibenzo-[b,f] [1,4]thiazepin-11-one, which is a representative compound of the dibenzothiazepine derivatives of the formula (5), is reacted with phosphorus oxychloride to yield a 11-chloro-dibenzothiazepine derivative; and to the 11-chloro-dibenzothiazepine derivative is added piperazine to yield a 11-piperazinyl-dibenzothiazepine derivative, which is subsequently reacted with 2-chloro-ethoxyethanol under basic conditions to give the desired 11-[4-(2-(2-hydroxyethoxy)ethyl]-1-=piperadinyldibenzothiazepin.
EP 0282236-A1 further describes that the dibenzo-[b,f] [1,4]thiazepin-11-one is prepared from phenyl 2-(phenylthio)phenylcarbamate or its analogous compound by cyclization in the presence of polyphosphoric acid.
Helv. Chim. Acta., vol. 42, pp. 1263 (1959) describes that a dibenzothiazepine derivative can be prepared by the steps of heating a methyl thiosalicylate derivative with a 2-halogenated nitrobenzene derivative in the presence of sodium to give a 2-nitro-2′-carboxy-diphenylsulfide derivative, which is then reduced using a Raney-nickel catalyst to yield a 2-amino-2′-carboxy-diphenylsulfide derivative, which is finally heated to give a dibenzothiazepine derivative.
Org. Prep. Proced. Int., pp. 287 (1974) describes that a dibenzothiazepine derivative can be prepared by the steps of heating a thiosalicylic acid ester derivative and 2-iodo-nitrobenzene derivative in the presence of sodium methylate and copper, treating the resulting compound successively with an alkaline solution and an acidic solution to give a 2-nitro-2′-carboxy-diphenylsulfide derivative, reducing the derivative by ferrous sulfate in an aqueous ammonia solution to give a 2-amino-2′-carboxy-diphenylsulfide derivative, and heating the resulting derivative under reduced pressure.
WO 92/19607 describes that a dibenzothiazepine derivative of the formula (5) can be prepared by the steps of reacting 2-aminothiophenol with 2-fluorobenzonitrile to give 2-(2-aminophenylthio)benzonitrile, hydrolyzing the resultant to give 2-(2-carboxyphenylthio)aniline, and finally cyclizing the aniline derivative.
As described above, various processes for preparing a dibenzothiazepine derivative of the formula (5) are known. However, the known preparing processes have various disadvantageous features such as a low yield, high temperature reaction conditions, use of starting compounds which are not easily available, and/or complicated post treatment. These disadvantageous features are naturally unfavorable in the industrial preparation of the desired dibenzothiazepine derivative.